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The presence of large numbers of potentially pathogenic microorganisms in water used for dental treatment justifies the implementation of scientifically validated treatment protocols for control of microbial contamination in dental unit waterlines.

Although the phenomenon of bacterial colonization of dental water delivery systems was first reported in 1963, most dentists were unaware of the issue until the mid-1990s. In 1995, the American Dental Association (ADA) convened an expert panel of researchers and policy makers to review the scientific evidence and to make recommendations to the profession.

While the panel confirmed that bacteria with the potential to cause disease were present in dental water systems, there was no scientific evidence suggesting an immediate public health crisis. Nevertheless, it was clear that the quality of water used in dental treatment should be improved. The panel was unanimous in agreeing that water used for dental treatment should meet or exceed the standards set for drinking water.

OSAP has endorsed the approach taken by the ADA and has worked with both the ADA and the Centers for Disease Control and Prevention (CDC) to encourage research and the sharing of information.

Since 1995, the number of approaches to improving dental water quality have increased dramatically. The Food and Drug Administration (FDA) has cleared numerous devices for use with the dental units, including bottled water systems, filters, and water purification units. The Environmental Protection Agency (EPA), which recently took over the regulatory jurisdiction for some chemical agents used in to improve dental water quality, is in the process of creating guidance for manufacturers who wish to register their products with antimicrobial claims. Awareness of this issue among practicing dentists has risen dramatically, and increasing numbers of dentists are taking measures to improve water quality.

In late 2003, the CDC issued updated guidelines for dental infection control including general recommendations for dental unit waterlines, biofilm and water quality. OSAP continues to support ADA and Centers for Disease Control and Prevention goals for improved treatment water quality. We remain committed to our mission to continuously improve the safety and quality of dental care delivered worldwide. This is underscored by a recent case report in the Lancet (Vol 379, February 18, 2012) about a woman in Italy who apparently contacted Legionella pneumophiliafrom a dental unit waterline during routine dental treatment. "Aerosolised water from high-speed turbine instrumentswas most likely the source of the infection." (Click HERE for more information)

Oral health staff members throughout the country should be familiar with the issue of dental unit waterline contamination and be prepared to discuss the issue with their patients. Following is the "What , Where , When , Why and How."

Bacterial growth is logarithmic in nature, and generation times for some waterborne organisms are measured in minutes. As such, untreated or improperly treated units can be quickly re-colonized from small numbers of "survivor" organisms.

In February, 2011, an 82-year-old woman was admitted to the intensive care unit with fever and respiratory distress. She was conscious and responsive. Chest radiography showed several areas of lung consolidation. She had no underlying disease. Legionnaires' disease was promptly diagnosed by Legionella pneumophila urinary antigen test; a bronchial aspirate was taken for microbiological examination. Oral ciprofloxacin (750 mg every 12 h) was started immediately. Nevertheless, the patient developed fulminant and irreversible septic shock and died 2 days later. An investigation to find the source of L pneumophila infection was initiated.

An 82-year-old Italian woman died after she contracted Legionnaires' disease, a severe, pneumonia-like illness, from the water in her dentist's office, according to a case report published in the journal The Lancet.

Dental chair units (DCUs) are used in the treatment of many patients throughout each day and microbial contamination of specific component parts is an important potential source of cross-infection. The quality of dental unit water is of considerable importance since patients and dental staff are regularly exposed to water and aerosols generated from the dental unit. This water hosts a diverse microflora of bacteria, yeasts, fungi, viruses, protozoa, unicellular algae and nematodes which may be contaminated with micro-organisms found in the biofilm formed due to water stagnation in the narrow-bore dental unit waterline (DUWL) tubings. The water thus contaminated, when used for various treatment procedures through dental handpieces, air/water/three-in-one syringe, etc., produces aerosols that can cause infection. The present review emphasises the risks of infection from DUWL and various water treatment procedures available to disinfect the DUWLs.

Three dental units with self-contained water systems in an outpatient teaching dental clinic were treated with a proprietary chlorine dioxide waterline cleaner. Three similar units were used as controls. After four weeks, test and control units were crossed over. Water samples were taken from each line on each unit and from the sink faucets at six time periods; and the frequency of use of each line was recorded. Statistical analysis showed that increased frequency of use of waterlines did not affect lines that were chemically treated, but was associated with less contamination of untreated lines.

This review concentrates on how practical developments and innovations in specific areas can contribute to effective DUWL biofilm control. These include the use of effective DUWL treatment agents, improvements to DCU supply water quality, DCU design changes, development of automated DUWL treatment procedures that are effective at controlling biofilm in the long-term and require minimal human intervention, are safe for patients and staff, and which do not cause deterioration of DCU components following prolonged use.

The specific structure of dental units favours the presence of biofilm and microbial contamination of the dental unit waterlines (DUWL) water. The ability of bacteria to colonize surfaces and to form biofilm in water supply tubes, including DUWL, is a common phenomenon, which has been well documented, just as with difficulties in biofilm removal and prevention of its regrowth. Microorganisms from contaminated DUWL are transmitted with aerosol and splatter, generated by working unit handpieces. On the basis of the detailed literature review, the state-of-the art knowledge of the microflora of dental unit waterlines is presented.

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